Winds
& The Coriolis Effect - Part 1
Do you know how the prevailing winds are formed? Wind begins to form when the sun heats an area of ground. As the ground warms the air, the particles of air move faster and spread out. The air becomes lighter and rises. Cooler air rushes in to fill the space below the rising warm air. This movement of air, or wind, is called a convection current. How does warming the ground create global winds?
Since more direct sunlight hits the water and ground near the equator, the air there is warmed the most. Air above the equator therefore warms more than air further north or south. Since the results that follow are complex, the results are developed in three components that are illustrated in the following applets. The first stage of the development of the prevailing winds is illustrated in the animation below. The winds shown are those that would be found on a planet much smaller than Earth and did not rotate.
In the animation, you can see that the warming of the air over the equator sets up a convection current that moves warmer tropical air towards the poles and draws cooler polar air towards the equator. This warmer air creates an area of low pressure as it rises. As this warmer air cools, it creates an area of high pressure. Next, you will see what would happen on a planet the same size as Earth but is not rotating.